Sunday, February 28, 2010
Wednesday, February 24, 2010
Vesta the asteroid is currently brighter than magnitude 6, and in the middle of the upside-down question mark that is the constellation Leo. Here's a pic from a panasonic Lumix digital camera on a 6 inch tripod. 60 sec exposure.
It's the upper of the two central green streaks.
The point of this is just to show that asteroids can be photographed with the family digital camera out the back window.
Monday, February 22, 2010
The denialists are the ones who threaten to rape young children.
via the ABC news:
An organised cyber-bullying campaign, including abusive emails, is targeting Australian climate scientists who speak out on climate change, according to author Clive Hamilton.
Climate campaigners have also noticed a surge in the frequency and virulence of this new form of cyber-bullying. The following was received by a young woman (who asked that her name not be used):
"Did you want to offer your children to be brutally gang-raped and then horribly tortured before being reminded of their parents socialist beliefs and actions?
Obviously this is a case of not enough post-docs doing outreach seminars.
Sunday, February 21, 2010
For people wondering what the whole climate debate is, the blog Skeptical Science at http://www.skepticalscience.com/ explains the difference between scientific evidence for positions and arguments for a position that don't actually stand up to critical thinking.
A useful site for anyone who finds a lot of the to-and-fro over their head.
Saturday, February 20, 2010
I have been working with uranium, either in U/Pb geochronology (small scale) or in mineral exploration (large scale), for a long time now. So some years back, I was googling around for information on the Oklo deposits- an old, rich African uranium deposit that became critical and lost much of its 235U through hydrothermally moderated fission.
What I found instead was this. This is a blog that has nothing at all to do with uranium, but instead describes the modeling and characterization of extrasolar planets. I thought that was pretty neat, and when they started discussing the possibility of extrasolar moons, I did a simple mass calculation to show that the chemistry was potentially interesting. The result of that dabble can be found here.
Since then, I have been working on a more formal description of extrasolar petrology, with an eye towards figuring out what bulk compositional variations will produce non-peridotitic condensates. This has meant more recreational science and less blogging, and is reason number two (after the expanding earth) that this place has been light-on.
And, as a reader pointed out fairly recently, I am not alone in this endeavor. A paper by Bond et al. was recently lofted into the arXiv on the very same subject, but with a somewhat different focus. Since the same reader asked my opinion, I wanted to say this:
Congratulations, Dr. Bond.
However, my main interests are in an area not covered by her team. This is not surprising, since she is an astronomer and I’m a geochemist. My approach has been petrological, and has mainly focused on the potential for nebular condensation of water-friendly phases, particularly cordierite.
As it turns out, I’ve been planning on attending the Goldschmidt conference as an exhibitor anyway. Ideally I would talk about SHRIMP related stuff there, but the developmental project I’ve been working on is not mature enough to present, and I don’t have the diplomatic skills necessary to convince laser ICPMS people that it is in their interest to let me use their data to show how shonky their techniques are. So I’ve submitted an abstract on the petrology of stellar condensation instead.
Normally, I would submit such an abstract a few minutes before the deadline, but the other night Mrs. Lemming pointed out that I had better finish the abstract immediately, as tweaking a figure from the birth suite was not an option. So it’s in.
The text, written at 2 in the morning, may be completely unintelligible. Y’all can see for yourselves- I’ve copied and pasted it below. If there are any egregious errors, please point them out before Sunday night American time- as abstracts are editable up until then.
The Petrology of Extrasolar Chondrites
The cosmochemical principle that the bulk composition of chondritic meteorites is similar to the spectrally-derived composition of the sun is extended to other stars. Extrasolar chondritic mineralogy is first derived via simple four-component CMAS normative calculations for 476 stellar chemical compositions from a variety of sources.
The most common exochondritic mineral assemblage in the CMAS system is the solar one: anorthite (an) - fosterite (fo) - enstatite (en) – diopside (di). It is closely followed by an-fo-en-cordierite (cd). Other assemblages combine for less than 10% of stellar compositions, and include such assemblages as: An-en-di-quartz (qz), an-en-qz-cd, an-fo-cd-spinel (sp), and fo-sp-various silica-poor Ca/Mg phases.
Equilibrium condensation calculations for major elements show that stars with higher C/O or Si/O ratios than solar can have insufficient H2O in the nebular gas to oxidize Mg, Si, Al, Ca during silicate condensation. Reduction of the nebular gas via silicate condensation leads to lower condensation temperatures for silicates, sulfide, silicide and nitride condensates, and CO breakdown into graphite and/or methane. Below 800K, this last reaction destabilizes the reduced condensates.
The percentage of stars with non-solar condensation sequences in a given survey ranges from fewer than 5% to more than 70%, depending on the study. Studies of stars from different research groups often lie in different mineralogical fields, and are not always within error of each other.
Figure 1: Equal-O projection of stellar compositions from anorthite into (truncated) fosterite-quartz-diopside and fosterite-quartz-spinel ternary diagrams. Circles: stars with planets; squares: stars without planets. Grayscaled by study.
(since this is the internet, grayscale is colored)
Wednesday, February 17, 2010
Sunday, February 14, 2010
Longtime readers will have noticed that the posting rate and quality have both drastically declined around here over the past 8 months. Truth is, I have been involved in a number of projects, the most important of which is the confirmation of the expanding Earth hypothesis. Truth be told, though, this is mostly Mrs. Lemming’s project; I just watch, listen, and tidy up all the other things that this doesn’t leave her time to do. But the demonstration of Earth expantion is going very well; the planet pictured below started out as just a wee little olivine just a few dozen weeks ago. Look at it now:
Tuesday, February 09, 2010
In the late ‘90’s and early 2000’s, there was a serious push in the west to stop the financing of rogue African militia by controlling “Blood Diamonds”. I’ve long been cynical of this approach. At the time, I was working in diamond research, and I saw far too many people leap on the blood diamond bandwagon as a way of getting additional research funding to direct to their pet projects. The fact that the program was eventually taken over by DeBeers as a marketing tool for solidifying their monopoly didn’t help either. And most importantly, I felt that diamond consumers were looking at the bloodless diamonds as a way of washing their hands of African problems and turning their backs on the continent.
Well, a decade on, and things are looking up for the diamond-producing parts of Africa. The civil wars in Angola, Liberia, and Sierra Leone are over. Botswana, Namibia, and South Africa are developing, and the latter country will be hosting the World Cup this year. But outside the cratonic cores of the continent, atrocities continue.
Yesterday, New York Times
blogger columnist Nicolas Kristof wrote a heartbreaking story about the mass killings and rapes that are still occurring in the Democratic Republic of Congo. Among the various proposals he listed for stopping the violence was, “we need a U.S.-brokered effort to monitor the minerals trade from Congo so that warlords can no longer buy guns by exporting gold, tin or coltan.”
So, what on earth is “coltan”? It’s a industry term for columbite-tantalum concentrate. Columbite is the ore of niobium, which is used in steels and high strength alloys. Tantalum, which is geochemically similar and thus found in the same deposits, is used mostly in capacitors for compact electronic devices such as personal computers and mobile phones. So the purchase of the device you are using to read this blog may have financed rape, mutilation, and genocide in central Africa.
From a technical point of view, identifying blood tantalite and niobate minerals should be much easier than dealing with diamonds. These minerals generally have enough uranium to allow uranium-lead geochronology, and are far more chemically complex than diamond. The main suppliers of tantalum (Brazil and Australia) are not Machiavellian DeBeers-like monopolists. Instead, they work using long-term, fixed-price contracts that should make identifying buys from the spot market relatively easy compared to the Byzantine marketing of diamonds. So the problem is tractable.
As it turns out, there are groups working to address this problem. http://www.enoughproject.org/conflict-minerals has links to proposed legislation currently in front of congress, as well as letters to the manufacturers of various electronic devices asking the companies to buy fair-trade HFSE’s. Just about the only thing they don’t have is a clever viral phone app to spread the word. But if any of you readers are clever programmers, why not spend the evening fighting genocide instead of reading blogs?
Tuesday, February 02, 2010
NASA's new administrator, Charlie Bolden, has outlined the administration's new plan for space exploration. He has a 10 page statement, but I think a picture is worth a thousand words:
Basically, the plan is to shut down the shuttle program, which was scheduled anyway. ISS access will be provided by the Russians, and any commercial companies that manage to compete with them. Shuttle infrastructure will be discontinued. And billions will be spent on the next new transformative technology.
The last time we threw away 20 years of launch technology in favor of the next newest, most efficient transformative technology, we canned Apollo for the shuttle. The cost overruns shut down American planetary exploration for a decade, and the end product was just as expensive and dangerous as the rocket it replaced.
Now they want to do it all again. And in the mean time, the only way to get to the International Space Station will be on Russian Soyuz- a system that has been incrementally improved and tested its debut in 1962.
In the mean time, sample return from anywhere appears to be off the table- even the R&D focuses on space biology, not landing and return technology. At least we have a SHRIMP in Russia and two in China- I suspect that's the closest I'll ever get to a macroscopic planetary sample in my professional lifetime.